A new approach to streaming media promises to improve the efficiency of existing streaming video systems. In a joint paper with informitv, presented at the SMPTE Annual Technical Conference in Hollywood, MediaMelon explained how its QBR system enhances existing ABR or adaptive bitrate streaming video to reduce the volume of data delivered by 30% or more, while protecting picture quality to improve the experience for users.
QBR uses perceptual quality analysis to provide information describing the visual complexity and encoding quality of media segments. This requires only a few bytes of additional data to describe each segment of video. This metadata enables a compatible media player to make smarter decisions about when to switch between different data rate encodings. It allows the player to optimize the download strategy according to network conditions and essentially plan ahead when to substitute segments of lower visual complexity and protect those that really require higher data rates.
Kumar Subramanian, the chief executive of MediaMelon, compared QBR to satellite navigation in a car. “Having a map showing the road ahead enables a driver to adapt better to the current conditions, which provides a smoother and more enjoyable experience,” he explained. “Quite simply, QBR enables smarter streaming by giving the media player hints that enable it to make more intelligent choices than conventional approaches.”
The paper presented at SMPTE is based on an evaluation by informitv, which reported average data rate reductions of 30-45% for QBR compared to conventional ABR delivery.
A test sequence, encoded at six different bitrates from 0.4Mbps to 3.5Mbps required an average data rate of just under 3Mbps with conventional ABR. With QBR it required just over 2Mbps in Quality mode and 1.6Mbps in Data mode, without compromising quality.
Even with a net reduction of 30%, the increased efficiency can be used to protect picture quality by delivering more complex scenes at a higher data rate than would otherwise be achieved.
The QBR compatible player generally requested segments representing low complexity scenes at a lower data rate than ABR, reserving capacity to request segments for more complex scenes at the highest quality encoding, while still reducing the overall mean data rate.
“Our study confirmed significant savings in the volume of data required to deliver equivalent or even improved picture quality, without any changes to the way the video was encoded or decoded,” reported Dr William Cooper of informitv.
Service providers can balance the benefits of reducing the cost of distribution or optimising quality, potentially by individual customer. The overall reduction in the volume of data delivered translates directly into savings in distribution costs or allows more streams to be served for the same cost.
QBR is backwards compatible with existing compression schemes. Integrations with popular encoders and players are already available, enabling service providers and media distributors to benefit from the improved performance.
‘QBR Metadata to Improve Streaming Efficiency and Quality’ was presented at the SMPTE 2017 Annual Technology Conference in Hollywood, California.